Virtualenvwrapper Installation and Usage

Enable at Shell Startup

Note that on CentOS systems we get an extra script, /etc/profile.d/virtualenvwrapper.sh. For those of you not familiar with the /etc/profile file and the /etc/profile.d directory (take a look at the end of /etc/profile), these locations correspond to system-wide startup files used by the Bourne shell (aka Bash) and Bourne compatible shells (ksh, ash, ...), and are sourced by your shell when you:

• login via TTY
• login via SSH
• launch a new shell

So, we should configure loading of the virtualenvwrapper in either

• /etc/profile
• /etc/profile.d/virtualenvwrapper.sh
• ~/.bashrc (user specific)
• ~/.profile (user specific)

and its content should be [1]:

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export WORKON_HOME=$HOME/.virtualenvs
export PROJECT_HOME=$HOME/Devel
source /usr/local/bin/virtualenvwrapper.sh

where WORKON_HOME is where your virtual environments will be stored, and PROJECT_HOME is the location of your development project directories (see [3]). The last line just loads all of the virtualenvwrapper methods.

After following the installation instructions above, you have to load the virtualenvwrapper methods, by launching a new shell, or if you already have a shell open you can source your startup file manually, i.e:

  ~$ . .profile

Managing your Virtual Environments

First let us see the command you will probably use the most workon that, when you do not pass any arguments, it shows a list of all the available virtual environments (located at WORKON_HOME)

~$ workon
~$

Well, we have not created any yet, so let us create a new one.

~$ mkvirtualenv AdS
Running virtualenv with interpreter /usr/bin/python2
New python executable in /home/t0rrant/.virtualenvs/AdS/bin/python2
Also creating executable in /home/t0rrant/.virtualenvs/AdS/bin/python
Installing setuptools, pkg_resources, pip, wheel...done.
(AdS) ~$ workon
AdS
(AdS) ~$

Looks good so let us install the sympy package for this environment

(AdS) ~$ pip install sympy
Collecting sympy
  Downloading https://files.pythonhosted.org/packages/dd/f6/ed485ff22efdd7b371d0dbbf6d77ad61c3b3b7e0815a83c89cbb38ce35de/sympy-1.3.tar.gz (5.9MB)
    100% |████████████████████████████████| 5.9MB 3.5MB/s
Collecting mpmath>=0.19 (from sympy)
  Downloading https://files.pythonhosted.org/packages/ca/63/3384ebb3b51af9610086b23ea976e6d27d6d97bf140a76a365bd77a3eb32/mpmath-1.1.0.tar.gz (512kB)
    100% |████████████████████████████████| 522kB 4.9MB/s
Building wheels for collected packages: sympy, mpmath
  Building wheel for sympy (setup.py) ... done
  Stored in directory: /home/t0rrant/.cache/pip/wheels/6c/59/86/478e3c0f298368c119095cc5985dedac57c0e35a85c737f823
  Building wheel for mpmath (setup.py) ... done
  Stored in directory: /home/t0rrant/.cache/pip/wheels/63/9d/8e/37c3f6506ed3f152733a699e92d8e0c9f5e5f01dea262f80ad
Successfully built sympy mpmath
Installing collected packages: mpmath, sympy
Successfully installed mpmath-1.1.0 sympy-1.3
(AdS) ~$

We can confirm that the sympy package is only available to this environment:

(AdS) ~$ python -m sympy.abc
(AdS) ~$ deactivate
~$ python -m sympy.abc
/usr/bin/python: No module named sympy
~$ workon AdS
(AdS) ~$

Assuming that we have a project called AdS, located in our PROJECT_HOME directory, we can associate the newly created environment to that project, via the setvirtualenvproject command [3]:

(AdS) ~$ cdvirtualenv
(AdS) ~/.virtualenvs/AdS$ setvirtualenvproject $PWD ~/Devel/AdS
Setting project for AdS to /home/t0rrant/Devel/AdS
(AdS) ~/.virtualenvs/AdS$ cdproject
(AdS) ~/Devel/AdS$ ls
AdS_sympy_test.py

As you can see we can now call cdproject which will take us to the project associated to the currently active virtual environment. Neat =)

Note: At this time (virtualenvwrapper v4.8.4) you can only have one project associated to one virtual environment (project foo should work with environment A), or one project associated with any number of projects (project bar should work with environments A, B, ..., Z), you cannot have one virtual environment associated with multiple projects. You can of course activate your desired virtual environment and use it within any directory, you will just not be able to use cdproject to change to the root directory of your project.

Just to check if the sympy is working in our environment:

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# AdS_sympy_test.py
#!/usr/bin/env python
from sympy import test

test("_basic")

(AdS) ~/Devel/AdS$ python AdS_sympy_test.py
============================= test process starts ==============================
executable:         /home/t0rrant/.virtualenvs/AdS/bin/python  (2.7.15-candidate-1) [CPython]
architecture:       64-bit
cache:              yes
ground types:       python
numpy:              None
random seed:        21534663
hash randomization: on (PYTHONHASHSEED=417663367)

sympy/core/tests/test_basic.py[16] ................                         [OK]

================== tests finished: 16 passed, in 0.06 seconds ==================
(AdS) ~/Devel/AdS$

Now we already did everything with this virtual environment so we exit it:

(AdS) ~/Devel/AdS$ deactivate
~/Devel/AdS$

and we can delete the virtual environment as our project development is now finished:

~/Devel/AdS$ rmvirtualenv AdS
Removing AdS...
~/Devel/AdS$ workon
~/Devel/AdS$

And we are done!